Swell Subcutaneous Fat
The third and bottom layer of the skin is called the subcutaneous (say: sub-cyoo-tay-nee-us) layer. It is made mostly of fat and helps your body stay warm and absorb shocks, like if you bang into something or fall down. The subcutaneous layer also helps hold your skin to all the tissues underneath it.

This layer is where you'll find the start of hair, too. Each hair on your body grows out of a tiny tube in the skin called a follicle (say: fah-lih-kul). Every follicle has its roots way down in the subcutaneous layer and continues up through the dermis. You have hair follicles all over your body, except on your lips, the palms of your hands, and the soles of your feet. And you have more hair follicles in some places than in others - there are more than 100,000 follicles on your head alone!

Your hair follicles rely on your sebaceous glands to bring on the shine. Connected to each follicle in the dermis layer is a tiny sebaceous gland that releases sebum onto the hair. This lightly coats the hair with oil, giving it some shine and a little waterproofing. Now that's good hair!

Working Together, Whatever the Weather!
The different parts of your skin are great at doing their own thing. But sometimes your blood vessels, hair, and sweat glands need to cooperate to keep your body at just the right temperature. If you were to run around in the heat or play outside when it's chilly, your body could get overheated or your inner temperature could drop. But your body is pretty smart. It knows how to keep your temperature right around 98.6 degrees Fahrenheit (37 degrees Celsius) to keep you and your cells healthy.

And that's where skin comes in. It responds to messages sent out by your hypothalamus (say: hi-poh-thah-luh-muss), the brain's inner thermometer. If you've been running around on a hot day, your blood vessels get the signal from the hypothalamus to release some of your body's heat. They do this by bringing warm blood closer to the surface of your skin. That's why you sometimes get a red face when you run around.

When your body needs to cool down, sweat glands also swing into action by making lots of sweat to release body heat into the air. The hotter you are, the more sweat your glands make! Once the sweat hits the air, it evaporates (this means that it changes from a liquid to a vapor) off your skin, and you cool down.

What about when you're ice skating or sledding and suddenly feel chilly? When you're cold, your blood vessels keep your body from losing heat by narrowing as much as possible and keeping the warm blood away from the skin's surface. You might also notice tiny bumps on your skin. Most kids call these goosebumps, but the fancy name for them is the pilomotor (say: pie-low-mo-ter) reflex. The reflex makes special tiny muscles called the erector pili (say: ee-reck-tur pie-lee) muscles pull on your hairs so they stand up very straight.

The Skin Wins!
When it comes to being one amazing organ, the skin wins! It covers us up, lets us feel the world around us, and helps keep us from getting hurt. The skin even provides some cushioning and temperature control for our bodies. Return the skin and protect your skin by playing it safe in the sun and always wearing sunscreen when you're outdoors. No matter what color skin you have, the UV rays can burn you or do damage that you might not even see or feel until you're older.

And unlike your lungs, your brain, or most other organs, your skin likes a good washing. When you wash your skin, use lots of water and a mild soap to make it nice and clean. Don't forget to cover scrapes and cuts with a gauze or bandage - this helps prevent infections and keeps your skin happy. Be sweet to your skin and it will stick close to you!

Updated and reviewed by: Kim Rutherford, MD
Date reviewed: October 2002